Before the invention of the light bulb, illuminating the world after the sun went down was a messy, arduous, hazardous task. It took a bunch of candles or torches to fully light up a good-sized room, and oil lamps, while fairly effective, tended to leave a residue of soot on anything in their general vicinity. With the invention of light bulb along and as the science of electricity really got going in the mid 1800s, the easy-to-use lighting technology was such an improvement over the old ways that the world never looked back.
Currently, the application of illuminating device can be categorized into two fields. One of which is the construction industry, that includes all sorts of lighting systems adapted for private housing units, commercial buildings, and public transportation systems like highway and railway, and so on, so as to achieve objects of comfort, beautification, and safety; another filed is the commercial goods, that includes all sorts of light source adapted for auto lamps, indoor lightings and consumer electronics, etc. As in the Year 2000, the largest demand for illuminating devices lays in the United State of American. Generally, the demand for illuminating devices is growing in a rapid path following the growth of global economy. Nevertheless, as the environmental awareness also grows with the global economy, it is in great demand to have green lighting systems for enhancing environmental protection and energy conservation.
Please refer to FIG. 1, which is a cross-section of a lighting system disclosed in U.S. Pat. No. 6,234,645, entitled “LED LIGHTING SYSTEM FOR PRODUCING WHIT LIGHT”. As seen in FIG. 1, the white lighting system 1 has at least three light-emitting diodes (LEDs) 11 for providing visible light at pre-selected wavelengths. In operation, the white lighting system 1 is provided with at least one fourth light-emitting diode 12 which, emits visible light in a further wavelength region, the maximum of the spectral emission of the fourth light-emitting diode 12 lying in the further wavelength region from 575 to 605 nm. Moreover, the screen 13 is provided on a side facing the LEDs 11, 12 with reflection means 14 which diffusely reflect white light so as to effectively blend the light of the LEDs 11, 12. However, the luminaire structure as disclosed in the U.S. Pat. No. 6,234,645 has low luminaire efficacy since it can not guide and scatter the rays emitted from the light source such that the referring lighting system 1 can not control the distribution of luminous intensity, not to mention the enhancement of luminance efficacy of a source of light while glare still can not be avoid.
In view of the abovementioned shortcomings, it is require to have an improved illuminating device with high luminaire efficacy for the sake of environmental conservation and also capable of reducing glare.